A new solution of arc-quenching chamber with double nozzles

The chamber rate voltage for the recent SF6 circuit breakers with the double graphite nozzles is limited under 300 kV due to the small distance between the nozzles. To avoid this problem we introduced a changing nozzle distance using the contact tube moving in the direction opposite to that of the contact fingers. This construction enables a higher relative velocity between the contacts at the opening of the circuit breaker and the faster establishment of higher withstand voltage between the moving nozzle and the opposite moving arcing ring. The gas blowing was rearranged for a good arc cooling in the new dynamic conditions.